VACCINES AND SERA 271 



iv. Cholera, Typhoid Fever, Plague. 



Cholera. — Human cholera is a toxic disease, the toxin 

 being secrfeted by the vibrios invading the intestine. The true 

 remedy for cholera, therefore, should be an antitoxic serum. 

 It was before our present conceptions as to the toxicity of the 

 cholera vibrio that Ferran, in 1884, tried to vaccinate men 

 against cholera by injecting the living microbe subcutaneously. 

 This method has been taken up and modified by Haffkine, 

 who has tried it in India, where cholera is always present. 

 In vaccinated individuals he found the mortality seven times 

 less than in the non-vaccinated, but although the death-rate 

 may be lower, the severity of the symptoms is quite as great 

 among the former as among the latter, which is rather dis- 

 concerting, as in other kinds of preventive vaccination this 

 does not occur. The solution of the cholera problem lies 

 elsewhere, but it is worth while recalling the attempts of Ferran 

 and Haffkine, because their method has proved of more value 

 in other diseases. 



Typhoid Fever. — Typhoid fever is a toxic enteritis, but 

 it is at the same time a blood-infection ; blood-cultures show 

 that there is septicaemia. The bacillus inhabits chiefly the 

 small intestine, but it also extends to the blood, the spleen, 

 and the bone-marrow. Hence there is much more hope of 

 success than with cholera for preventive injections of the 

 bacteria under the skin. Bacilli killed by heat are employed. 

 The injection produces some swelling and pain with fever and 

 stiffness the discornfort lasting about two days. Two, or even 

 three, injections ought to be made. The treatment is succeeded 

 by what is called a "negative phase," during which the 

 individual may be in a condition of lowered resistance. 



Anti-typhoid vaccination has been chiefly employed hitherto 

 in the English army in India, in the Transvaal, in Egypt, and 

 in Cyprus. A certain number of the inoculated individuals 

 have nevertheless taken the disease (in many of these the 

 vaccination had been insufficient), but in a form milder and 



